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18.1 Introduction to Acids and Bases

Notes 14 - Properties of Acids and Bases

• Acids taste sour. Bases taste bitter and feel slippery.

• Acids and bases are conductors of electricity.

• Acids and bases can be identified by their reactions with some metals and metalsome metals and metal carbonates.

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18.1 Introduction to Acids and Bases

• Acids turn blue litmus red

Properties of Acids and Bases (cont.)

• Acids turn blue litmus red.• Bases turn red litmus blue.

• Magnesium and zinc react with acids to produce hydrogen gashydrogen gas.

• Geologists identify limestone because it produces bubblesbecause it produces bubbles of carbon dioxide when exposed to hydrochloric acid.p y

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18.1 Introduction to Acids and Bases

• All water solutions contain hydrogen ions (H+)Properties of Acids and Bases (cont.)

All water solutions contain hydrogen ions (H ) and hydroxide ions (OH–).

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18.1 Introduction to Acids and Bases

• An acidic solution contains more hydrogenProperties of Acids and Bases (cont.)

An acidic solution contains more hydrogen ions than hydroxide ions.

A b i l ti t i h d id i• A basic solution contains more hydroxide ions than hydrogen ions.

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18.1 Introduction to Acids and Bases

The Arrhenius ModelThe Arrhenius modelThe Arrhenius modelstates that an acid is a substance that contains hydrogen and ionizes to produce hydrogen ions in aqueous solution and aaqueous solution, and a base is a substance that contains a hydroxide group y g pand dissociates to produce a hydroxide ion in solution.

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18.1 Introduction to Acids and Bases

The Arrhenius Model (cont.)

• Arrhenius acids and bases• Arrhenius acids and bases

– HCl ionizes to produce H+ ions.

– HCl(g) → H+(aq) + Cl–(aq)

– NaOH dissociates to produce OH–

iions.

– NaOH(s) → Na+(aq) + OH–(aq)

– Some solutions produce hydroxide ions even though they do not contain a hydroxide group.contain a hydroxide group.

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18.1 Introduction to Acids and Bases

The Brønsted-Lowry Model• The Brønsted-Lowry Model of acids andThe Brønsted Lowry Model of acids and

bases states that an acid is a hydrogen ion (proton) donor, and a base is a hydrogen i ( t ) tion (proton) acceptor.

• The Brønsted-Lowry Model is a more inclusive model of acids and bases.

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18.1 Introduction to Acids and Bases

• A conjugate acid is the species produced The Brønsted-Lowry Model (cont.)

j g p pwhen a base accepts a hydrogen ion.

• A conjugate base is the species producedA conjugate base is the species produced when an acid donates a hydrogen ion.

• A conjugate acid-base pair consists of twoA conjugate acid base pair consists of two substances related to each other by donating and accepting a single hydrogen ion.

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18.1 Introduction to Acids and Bases

H d fl id B t d L id

The Brønsted-Lowry Model (cont.)

• Hydrogen fluoride—a Brønsted-Lowry acid

– HF(aq) + H2O(l) ↔ H3O+(aq) + F–(aq)

– HF = acid, H2O = base, H3O+ = conjugate acid, F– = conjugate base

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18.1 Introduction to Acids and Bases

A i B t d L b

The Brønsted-Lowry Model (cont.)

• Ammonia— Brønsted-Lowry base

– NH3(aq) + H2O(l) ↔ NH4+(aq) + OH–(aq)

• Water and other substances that can act as id b ll d h t iacids or bases are called amphoteric.

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18.1 Introduction to Acids and Bases

• An acid that can donate only one hydrogen Monoprotic and Polyprotic Acids

y y gion is a monoprotic acid.

• Only ionizable hydrogen atoms can be• Only ionizable hydrogen atoms can be donated.

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18.1 Introduction to Acids and Bases

• Acids that can donate more than one Monoprotic and Polyprotic Acids

hydrogen ion are polyprotic acids.